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How Autism Spectrum Disorders are Diagnosed

written by: Sandi Johnson • edited by: Paul Arnold • updated: 2/10/2011

To reach specific autism spectrum disorders diagnosis, doctors take several approaches. Often, professionals from multiple disciplines consult to reach a final determination.

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    Even with Diagnostic Criteria, Diagnosis is Subjective

    According to the DSM-V, autism spectrum disorders diagnosis must meet specific criteria. However, even with specific diagnostic criteria, much of the process is subjective. There are, as yet, no clear, conclusive laboratory tests for diagnosing autism spectrum disorders. Unfortunately, much of the diagnostic process is left to deciphering parental reports, medical histories, clinical observations and checklists. It is for this reason that experienced parents and autism spectrum experts often recommend seeking out a multidisciplinary team to help diagnose a child suspected of having an autism spectrum disorder.

    autism diagnosis While no specific blood test, MRI, or other laboratory-type method is yet available to provide a concrete confirmation, these tests and other evaluations provide the clues doctors need. For example, genetic testing does not prove an autism spectrum disorders diagnosis, but it can rule out other possibilities such as Fragile X Syndrome. Similarly, speech and occupational evaluations help highlight specific skill deficits that further support a diagnosis on the spectrum.

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    Diagnosing Autism Spectrum Disorders: The Process at a Glance

    In most cases, parents or school personnel are the first to notice signs of autism spectrum disorders. These individuals may only know that something is simply not right with a child. Often, the child receives a referral to a school psychologist, private practice psychologist, or developmental pediatrician to determine the cause of poor social skills, articulation difficulties, or other troublesome signs.

    At the initial appointment for evaluation, parents provide medical history, including pregnancy information and events, early infant or toddler milestone timelines, and current behavioral information. The medical professional, whether psychologist, psychiatrist, or developmental pediatrician typically performs a series of checklist-based tests and observes the child playing and interacting with others.

    Aspects of the child's developmental history, such as when he or she first spoke, walked, rolled over on their own, and other milestones are noted. The child's willingness to interact with others is evaluated. Language and spontaneous speech are evaluated. Behaviors such as hand-flapping and other self-stimulating behaviors either reported by parents and care givers or as observed during evaluation are noted.

    Results, medical histories, and parental reports are weighed against the diagnostic criteria in the DSM-V. Testing may require one appointment for an hour or two or several appointments over a few weeks. The doctor may also request medical records from pediatricians and reports or completion of checklists by school personnel and other care givers.

    Based on the results of the initial testing, doctors make initial autism spectrum disorders diagnosis that either specifies an ASD or notes the need for more testing to determine exact diagnosis. Depending on the specific test results, the medical professional may request further evaluations and testing by other professionals such as speech, physical, or occupational therapists, blood work by a geneticist, or other laboratory-based testing.

    These initial tests and consultations between multidisciplinary teams can often pinpoint a specific disorder when routine psychological testing does not offer a clear answer. Evaluation by other disciplines also helps the primary medical care provider with recommendations for treatment plans, academic or home supports, and other interventions.

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    Autism Spectrum Disorder Diagnosis - Who Tests What?

    Psychologists and psychiatrists use specific tests such as:

    • ADI-R (Autism Diagnostic Interview)
    • ADOS (Autism Diagnostic Observation Scale)
    • CARS (Childhood Autism Rating Scale)
    • CHAT or M-CHAT (Checklist for Autism in Toddlers)
    • Pervasive Developmental Disorders Screening Test 2

    Speech and Occupational Therapists use therapeutic evaluations that measure:

    • Vestibular system function (balance)
    • Tactile system function (sense of touch)
    • Proprioceptive system function (body awareness)
    • Learning language skills (phonemic memory, working verbal memory)
    • Expressive language skills (speaking, using words meaningfully)
    • Receptive language skills (the ability to comprehend spoken language)

    Geneticists use specific genetic tests for autism spectrum disorders diagnosis, more to rule out other possible disorders. However, some tests show promise for confirming an autism spectrum diagnosis. Common genetic tests include:

    • Chromosomal microarray analysis (CMA)
    • Fragile X testing
    • G-band karyotype testing
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    References and Resources

    National Autism Association, How is Autism Diagnosed http://www.nationalautismassociation.org/diagnosis.php

    Coffs Coast Autism, Diagnostic Process http://www.coffscoastautism.org.au/content/diagnostic-process

    Oklahoma Autism Alliance http://www.okautism.org/signs-of-autism/

    New York Daily News, MRI Testing for Autism http://www.nydailynews.com/lifestyle/health/2010/12/02/2010-12-02_autism_breakthrough_mri_tests_shown_to_be_highly_accurate_at_diagnosing_disorder.html

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